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A007345
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Number of Havender tableaux of height 2 with n columns.
(Formerly M3575)
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2
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1, 4, 21, 127, 831, 5722, 40879, 300440, 2258455, 17291704, 134417955, 1058279251, 8422155293, 67647554826, 547699155261, 4465275681735, 36627214297455, 302067234113560, 2503174651819435, 20832888975309257, 174057811108059017, 1459365504991034106
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,2
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REFERENCES
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D. Gouyou-Beauchamps, "Tableaux de Havender standards," in S. Brlek, editor, Parallélisme: Modèles et Complexité. LACIM, Université du Québec à Montréal, 1989.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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D. Gouyou-Beauchamps, Tableaux de Havender standards, Parallélisme: Modèles et Complexité. LACIM, Université du Québec à Montréal, 1989. (Annotated scanned copy)
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FORMULA
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G.f.: (sqrt(1-5*x^2) - sqrt(1-9*x^2)) / (2 * x^2 * sqrt(1-x^2)) [from Gouyou-Beauchamps]. - Sean A. Irvine, Dec 28 2017
a(n) = Sum_{q=0..2*n} Sum_{j=max(0, n-q)..floor((2*n-q)/2)} n! * (4*n-2*q-2*j)! / ((2*n-q-2*j)! * (j+1)! * ((2*n-q-j)!)^2 * (q-n+j)!) [from Gouyou-Beauchamps]. - Sean A. Irvine, Dec 28 2017
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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